#define D(s) s=p[e++]-48;while(p[e]!=46&&p[e])s=10*s+p[e++]-48;e++;
void main(int c,char**a){int t,z=0,x=0,e;char*p=*a;c=12;while(c--){gets(p);e=0;D(t)z+=t;D(t)x+=t;}t=z/12;x+=z%12*100;e=x/12;if (x%12>6)e++;printf("$%d.%d",t,e);}